Learn How to Block Unknown Callers on Your Phone

Understanding Unknown Caller Blocking and Why It Matters

Unknown callers are a growing problem for phone users. According to the Federal Communications Commission (FCC), Americans received approximately 3.7 billion robocalls in 2022 alone. These unwanted calls include spam, scams, telemarketing pitches, and potentially fraudulent schemes designed to steal personal information or money. Many people find these interruptions frustrating, whether they occur during work, family time, or sleep.

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Blocking unknown callers means stopping calls from numbers that are not in your phone's contact list or that use technology to hide their identity. This guide explains the tools and methods available on both iPhone and Android devices that allow you to screen out these unwanted communications.

The primary reason to block unknown callers involves personal safety and peace of mind. Scammers frequently use spoofed numbers—fake caller IDs that appear to be from legitimate businesses, banks, or government agencies—to trick people into revealing passwords, Social Security numbers, or financial information. A 2021 AARP study found that people aged 18 and older lost over $1 billion to phone scams in that year, with many victims targeted by unknown callers.

Beyond scams, unknown callers can include telemarketers, robocalls promoting products or services, and automated calls from companies you've never done business with. While some of these are legal, they waste time and create unwanted interruptions. Blocking options range from built-in phone features to third-party apps that provide additional filtering.

Practical Takeaway: Understanding the difference between legitimate calls and spam helps you decide which blocking method works best for your situation. The following sections describe specific tools and steps you can take on your device.

Built-In iPhone Features for Blocking Unknown Callers

Apple's iPhone includes a native feature specifically designed to reduce unwanted calls. The "Silence Unknown Callers" option automatically sends calls from numbers not in your contacts to voicemail and mutes the notification sound. This feature became available starting with iOS 13 (released in 2019) and works on all iPhone models running that operating system or newer.

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To enable this feature, open the Settings app and navigate to Phone. Scroll down to the "Calls" section and look for "Silence Unknown Callers." Toggle this option on. When activated, only calls from people in your Contacts, recent outgoing calls, or Siri suggestions will ring through normally. All other incoming calls go directly to voicemail without interrupting you.

The benefit of this approach is that it doesn't permanently block anyone—voicemail remains available, and legitimate callers can leave messages. If someone tries to reach you from a number you don't recognize, they can still leave a voicemail, and you can retrieve it at your convenience. This preserves contact from people who genuinely need to reach you, such as medical offices, delivery services, or new contacts, while filtering out most spam and scam attempts.

Beyond the native silencing feature, iPhone users can manually block specific numbers. When a call comes in, swipe up to reveal additional options and select "Block this Caller." Alternatively, open the Phone app, find the number in your recent calls list, tap the information icon (i), scroll down, and select "Block this Caller." Blocked callers cannot reach you via phone calls or FaceTime, and their texts appear in a separate folder within Messages.

For additional filtering, iPhone offers integration with third-party apps through the Settings app. Some carriers also provide call filtering services that work alongside your iPhone's built-in tools. Verizon Call Filter, AT&T Call Protect, and T-Mobile Scam Shield are examples of carrier-provided services that can work in tandem with iPhone's native features.

Practical Takeaway: Enabling "Silence Unknown Callers" on your iPhone provides an immediate reduction in unwanted interruptions while preserving voicemail access. This single setting requires no additional apps or subscriptions and works passively in the background.

Android Phone Options for Unknown Caller Blocking

Android devices offer similar blocking capabilities through both built-in features and third-party applications. Google's native Phone app (available on most Android devices) includes a "Block Unknown" or "Filter Unknown Calls" feature that automatically sends unidentified callers to voicemail or declines calls from numbers not in your contacts.

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To access this feature on Android, open the Phone app and tap the menu button (three vertical dots). Select Settings, then navigate to Caller ID and Spam. Look for options such as "Filter Unknown Calls," "Block Unknown Callers," or "Spam and Call Screen." Toggle the appropriate option on. The exact naming and location vary depending on your Android version and device manufacturer, but this path works for most Google Pixel phones and many Samsung devices.

Samsung phones specifically include their own call filtering system. On Samsung Galaxy devices, open the Phone app, tap the menu, select Settings, then Call Rejection. From there, you can enable "Auto Reject Unknown" to send calls from unknown numbers directly to voicemail. Samsung also allows you to create a rejection list and customize how the phone handles different types of calls.

For users who want more detailed control, Google Play Store offers numerous third-party call-blocking apps. Truecaller is one of the most widely used, with over 500 million downloads. This app identifies and blocks spam calls based on a crowd-sourced database of known spam numbers and scam patterns. TrueCaller shows caller names and identifies which calls are spam before they reach you, allowing you to decline them automatically.

Other popular Android call-blocking apps include RoboKiller (which uses artificial intelligence to identify robocalls and scam patterns), Nomorobo (a service originally designed for landlines that also works on mobile devices), and Whoscall (which provides caller identification and blocking). Many of these apps offer both free and paid versions, with paid versions typically offering enhanced filtering, detailed reports, and priority support.

Practical Takeaway: Android users can start with their phone's built-in call filtering options before installing third-party apps. Most Android devices include native features that rival iPhone's capabilities and require no additional cost or setup beyond enabling a toggle in Settings.

Understanding Carrier-Provided Call Filtering Services

Your mobile carrier—whether Verizon, AT&T, T-Mobile, or another provider—offers call filtering and blocking services. These services work at the network level, meaning they filter calls before they even reach your device. Carrier services often provide more comprehensive filtering than individual phone settings because they analyze call patterns and data across millions of users.

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Verizon offers Call Filter, which comes in a free version and a paid premium tier. The free version identifies known spam calls and shows you which calls are likely spam before you answer. The premium version ($3.99 per month) adds reverse phone lookup, blocks spam calls automatically, and provides detailed call logs and reporting. Call Filter integrates directly with Verizon's network, making it effective at catching spoofed calls before they reach your phone.

AT&T Call Protect works similarly, offering a free tier and a premium "Call Protect Plus" ($4.99 per month). The free version identifies suspected spam calls and blocks known scam numbers. Premium adds automatic blocking, detailed analytics about blocked calls, and the ability to create custom block lists. AT&T customers can manage their settings through the AT&T Mobile app or online account portal.

T-Mobile Scam Shield is included at no cost for most T-Mobile customers. This service automatically identifies and blocks known scam calls, robocalls, and spam numbers before they reach your phone. T-Mobile also offers Scam Shield with advanced features for a small monthly fee, which includes caller name display and more aggressive filtering.

Independent carriers and regional providers may offer their own versions of call filtering. Sprint (now merged with T-Mobile), US Cellular, and other carriers typically have specific services documented on their websites or available through account settings. Many carrier services also protect against text scams and phishing attempts, not just voice calls.

One advantage of carrier-level filtering is that it protects your phone number from being contacted by spam systems in the first place. When a carrier blocks a spam call, that system knows not to retry your number, reducing the volume of unwanted attempts over time. This differs from phone-level blocking, which only stops calls that reach your device.

Practical Takeaway: